1. The Field of the Invention
The present invention relates to the field of optical communication and optical links. More particularly, embodiments of the invention relate to an optical bus and to an optical sub assembly used in an optical bus.
2. The Relevant Technology
When people think of computers, conventional desktop systems and laptop computers often come to mind. Common uses of computers include school or work related issues. Upon further reflection, however, it becomes clear there are many different types of computers that are used directly or indirectly by people every day. Often, these computers are part of a system that monitors or controls peripheral components.
For example, there are many systems operating today that are computer controlled. Often, these computer systems are connected with external components that are used for varying purposes such as data collection or data output. A computer, for example, may be connected with multiple sensors. The data provided by these sensors can be collected and evaluated by the computer. The evaluation of the collected data can lead to certain actions in the system. Cars, for example, typically include a computer to monitor various aspects of the car's operation. Monitoring the car's operations is achieved using sensors that provide data to the computer or that provide a signal back to the computer indicating that a certain condition is true or false.
A car's braking system, air bag deployment system, traction control system, and the like are examples of the car's operation that are monitored and/or controlled by a computer. By monitoring these aspects of the car's operations, the car is able to provide certain benefits to the occupants. The computer can ensure, for example, that the brakes do not lock, that the air bags deploy in an accident, that the wheels do not slip, and the like or any combination thereof.
The ability of a computer to interact with remote sensors or other peripherals of a system or to interact with other computers often requires a bus or other communication path. The bus includes the wires that are needed to ensure that the computer can communicate with the peripheral device. Generally stated, a bus is a group of electrical lines that are used to transmit control information as well as data. The use of wires in the bus, however, begins to present problems as the number of peripheral devices increases.
For example, a control module may interface with multiple sensors or other peripheral devices. Typically, at least three wires are required for each device. Two of the wires provide power and ground. The third wire typically carries a control and/or data signal to and from the device. In some cases, two wires are used to convey the signal to and from the device. As the number of peripheral devices increases, the number of wires needed for the bus has a corresponding increase. It is likely, therefore, that a given bus between a control module or computer and its peripheral devices may require hundreds of wires. The large number of wires makes the system large and unwieldy, difficult to troubleshoot, and the like. Further the ability to expand or make improvements to such a system is difficult in view of the system's size and complexity.
One of the alternatives to an electrical wire bus is to utilize optical links. In conventional systems, optical links have certain advantages that are not present in wire based links. Advantages of optical links include, for example, wide bandwidth, low loss, electromagnetic immunity, and the like. These advantages often make an optical system preferable to an electrical system.
However, optical based systems also have certain limitations. Optical links are point to point links, which means that two transceivers are required for each link. This further suggests that two optical fibers are also required for each link if bidirectional communication is desired. Systems that are based on optical point to point links require 2N transceivers where N is the number of links in the system. In D WHW practical terms, implementing a conventional optical bus may require a control module or computer to have a separate transceiver for each of the peripheral devices.
As a result, an optical system is soon faced with some of the same problems that are present in an electrical bus as discussed above. What is needed is an optical bus and/or an optical sub assembly that can reduce the number of transceivers required for an optical system as well as reduce the number of fibers that would be included in the system.